It is known that a disk brake for a wheel comprises one or more disks constrained to rotate with the wheel, together with an actuator capable of applying axial pressure on the disks to brake the wheel. Generally, when the brake includes a plurality of disks, at least some of them, while remaining constrained to rotate with the wheel, are nevertheless mounted so as to be capable of sliding parallel to the axis of said wheel.
Essentially two types of disk brake are known that differ with respect to raw material, namely brakes with metal disks and brakes with carbon disks.
In brakes with metal disks, the said disks are made of steel, cast iron, copper, etc. . . . , and an actuator presses brake linings against said disks which brake linings may be made, for example, of asbestos fiber and phenol resin, a vitrified compound, a ceramic-metal compound, etc. In brakes having carbon disks, the said brake linings are likewise made of carbon.
Each of these two types of disk brake has its own advantages and drawbacks.
With brakes having metal disks, wear performance is good at low power per cm.sup.2, and the cost of brake lining material is low. In contrast:
wear performance falls off rapidly when braking at high power per cm.sup.2 ; and
energy storage for given mass is low because of the specific heat and the poor refractory nature of the material used for the linings and for the disks.
In brakes having disks and linings made of carbon: at low power per cm.sup.2, wear performance is of the same order as that of the linings in brakes having metal disks;
at high power per cm.sup.2, wear performance is considerably better than that of the linings in brakes having metal disks; and
energy storage for given mass is high because of the refractory nature and the high specific heat of carbon.
In contrast, the cost of carbon is high, and as a result each braking operation is expensive.
An object of the present invention is to remedy the above drawbacks and to provide a disk brake having the advantages both of brakes having metal disks and of brakes having carbon disks, but without their drawbacks.